The present invention relates to a method for lining pipes in a pipeline such as town gas pipeline or water pipeline, and more particularly to a method for lining pipes with plastics in order to repair old pipes.
A conventional lining method for old pipes is that fine droplets of thermosetting plastics such as epoxy resin are carried through the pipes by airstream produced by a compressor or blower, so that the inner walls of the pipes may be coated with the plastics. In the conventional method, the velocity and pressure of carrier air are comparatively high, for example the velocity is 80 m/sec.-100 m/sec. and the pressure is 2 Kg/cm.sup.2 -7 Kg/cm.sup.2. Under conditions of high velocity and pressure of carrier air plastics having a low viscosity is liable to move on the inner wall of pipe without sticking to the inner wall. Accordingly, viscosity of the plastics for the lining should be held to a high value. However, plastics having a high viscosity is hard to be pulverized and to spread on the inner wall. Therefore, such a plastics does not uniformly adhere to the inner wall.
On the other hand, the majority of old pipes are pierced with a plurality of holes caused by corrosion. Accordingly, plastics supplied at a high pressure flows out through the holes, so that the holes are not blocked with the plastics.
In addition, it may happen that the holes are expanded or the pipes are broken by the plastics.